The present invention relates to an image compensation apparatus, and particularly to an image compensation apparatus for compensating an attitude of image pickup section capable of rotating around three axes (roll axis, pitch axis and yaw axis).
In recent years, a technique for assisting pilot control by acquiring image information about the outside world in flight by a predetermined image pickup device and generating outside world video based on this image information and displaying the generated outside world video on a predetermined display is proposed and commercialized.
For example, a technique in which a video camera (for example, see patent reference 1) mounted in a gyroscopic driving device capable of rotating around mutually orthogonal three axes and arbitrarily changing an image pickup direction is attached with an outside of aircraft is proposed. When such a gyroscopic driving device is adopted, even in case that the aircraft encounters gust, outside world video is maintained in a stable state by gyro stabilizing effect.
On the other hand, in the case of controlling an aircraft, a technique for providing outside world video (image information) which changes in response to movement of a head or a sight line of a pilot while properly showing an inclination of the horizon or a flight direction as well as the stable outside world video described above is required.
As the technique for providing such image information, a system (hereinafter called “an enhanced vision system”) in which a small display (Head Mounted Display: hereinafter called “HMD”)is mounted on a head of a pilot and also a camera is installed on an aircraft through a predetermined driving device and a sight line direction of the pilot is detected by measuring movement of the head of the pilot and the camera is driven according to the detected sight line direction is proposed (for example, see patent reference 2).
[Patent Reference 1]
JP-A-5-167901 (Page 2, FIG. 2)
[Patent Reference 2]
JP-A-2001-344597 (Page 1, FIG. 1)
However, the driving device used in the image information providing system as described above has a structure in which a camera can be rotated only around two axes (pitch axis and yaw axis), so that a pilot (or a co-pilot) visually identifying image information provided by this system may have physiological discomfort.
For example, when an aircraft moves to pitching direction in a state in which a pilot turns toward the side temporarily and thereby a camera rotates around a yaw axis, the image information is displayed as if the aircraft had performed roll movement. On the other hand, since the aircraft actually does not perform the roll movement, the pilot feels that the aircraft performs the pitching movement by vestibular organs made of semicircular canals and ear stones. As a result of this, a contradiction between image information obtained from eyes by the pilot and space information obtained from the vestibular organs arises, so that the pilot tends to get travel-sick.
Such a phenomenon becomes remarkable in the case that the pilot cannot see the outside at all or in the case that it is difficult for the pilot to see the outside (for example, at the time of night or bad weather conditions in the case of using a see-through visual display system).